A man robbed a One Stop store in Milton Keynes on Thursday night after threatening staff with a knife and hammer.
The offender entered the shop in Knebworth Gate, Giffard Park, just before 11pm, demanding money from two members of staff and threatening them with the weapons.
The offender took cash before running away towards Blakelands.
He is described as white, in his late twenties to early thirties, about 5ft 8ins, and of medium build.
He was wearing a black hooded top, blue jeans and gloves.
Det Con David Brandon said: “I would appeal to anyone with any information to contact police immediately. I would especially appeal to anyone who recognises the description of the offender to call me via the Thames Valley Police Enquiry Centre on 101.
“I would like to reassure local residents that we are conducting a thorough investigation into the offence.
“If you don’t want to speak directly to the police you can contact Crimestoppers, anonymously, on 0800 555 111 or online at www.crimestoppers-uk.org No personal details are taken, information is not traced or recorded and you will not go to court.”